Continuous drying of endless filaments



Jan. 4, 1955 E. TORKE ET AL.

commuous DRYING 0F ENDLESS FILAMENTS 2 Sheets-Sheet 1 Filed Nov. 3, 1951 Jan. 4, 1955 TORKE ETAL CONTINUOUS DRYING OF ENDLESS FILAMENTS 2 Sheets-Sheet 2 Filed Nov. 3, 1951 3y MEI-117A Jim/Mm- United States PatentO CONTINUOUS DRYING F ENDLESS FILAMEN TS Erich T orke and Fritz Koch, Hamburg-Othmarschen, and

Wilhelm Diem, Krefeld, Germany, assignors to Phrix- Werke Aktiengesellschaft, Hamburg, Germany, a corporation Application November 3, 1951, Serial No. 254,785

Claims priority, application Germany November 16, 1950 Claims. (Cl. 34-62) This invention relates to improvements in the continuous drying of endless filaments. It more particularly relates to a method and apparatus for continuously drying an endless passing filament in an untensioned condition.

In conventionally known methods endless fibre strands are placed in loose loops on a conveyor belt with a transverse motion and passed on this belt through a drying zone in an untensioned position. lnasmuch as the individual filament, having for example, an average count of about 150 deniers, is extremely light in weight, it is not easy according to the conventional methods to place the filament in loose loops on the conveyor belt. The light filaments may be blown upward by the air current rising from the hot dryer, so that an entangling of the filament can very easily take place, which makes the subsequent reeling or twisting difficult.

One object of this invention is the placing of endless fibre strands in loose loops on a conveyor belt for drying in an untensioned condition in a positive and sure manner and without the above-mentioned difiiculties. This, and still further objects will become apparent from the following dlfscription read in conjunction with the drawings, in whic Fig. 1 is a side sectional view of a dryer in accordance with the invention with a positive guide for placing the filament on the conveyor belt;

Fig. 2 is a side sectional view of a different embodiment of a dryer with guiding means, in accordance with the invention;

Fig. 3 is a top elevation of a bar type draw-off roll which may be used in accordance with the invention;

Fig. 3a is a side elevation of the bar type draW-ofi roll shown in Fig. 3;

Fig. 4a diagrammatically shows a filament being drawn off on a bar type draw-off roll; and

Fig. 4b diagrammatically shows the draw-ofi roll in Fig. 4a in a different position of rotation.

In accordance with the invention the filament is passed downward and guided onto an endless conveyor belt by means of a gas current moving co-current therewith. The filament so guided on the endless conveyor belt is passed in an untensioned condition on this belt through a drying zone where it is dried by means of heat. The filament may be passed downward through a guide shaft through which the guiding gas current is also passed in a downward direction. The guide shaft, for example, may be provided with a filament inlet nozzle below which cold or hot air currents conduct the filament to the conveyor belt. It is also possible to leave the guide shaft open and produce the guiding air current by drawing air from an otherwise closed drying chamber.

The laying of the filament in loose loops on the moving conveyor belt may be effected in any known or conventional manner, such as by a lateral reciprocal motion of the conveyor belt or of the guide member feeding the filament to the shaft. If a feed nozzle is used in accordance with the invention, it may also be used to produce the transverse motion necessary for forming the loose loops on the conveyor belt.

In accordance with the invention the use of a bar type draw-off roll has proven particularly adaptable as the last filament guide member for guiding the filament downward through the guide shaft and guiding gas current onto the conveyor belt. Such a bar type draw-off roll consists of multiple bars parallelly positioned around an axis of rota- "ice tion. The filament is grasped by the individual parallel bars and not by a solid cylindrical surface as in the case of conventional solid draw-ofi rolls. The filament will be conducted around this bar type draw-01f roll in a linearly direction between adjacent bars and therefore with a number of angles. This will result in an increase of the frictional resistance of the filament as compared with solid cylindrical draw-off rolls. This frictional resistance is furthermore increased by the fact that the liquid given 01f by the filament to the draw-off rolls evaporates due to the air current which passes between the bars without any impediment as the roll rotates. In the case of conventional solid draw-off rolls, this liquid does not evaporate as rapidly and leads very quickly to the lubrication of the solid draw-off roll surface which decreases the friction between the filament and this surface. The filament will always readily disengage in a uniform manner from the dry bars of the bar-type draw-off roller in direct contrast to solid draw-off rolls in which the filament adheres to the moist surface of the draw-off roll so that a dependable laying of the filament on the conveyor belt is not possible. If solid draw-ofi rolls are used and are to place the filament on the conveyor belt in loose loops, they must be imparted a reciprocating motion transverse to the downward direction of the filament. The bar type draw-off rolls used in accordance with the present invention will automatically produce oscillations in the freefalling filament, so that the latter is laid in loose loops on the conveyor belt without any lateral reciprocation of the guide member or the conveyor belt or any other transverse motion device being required.

The filament is laid on the conveyor belt in loose loops and is passed on this belt through a drying zone. The drying in the drying zone may be effected in any desired manner, as, for example, by infra-red radiation, hot air, superheated steam, high frequency induction or capacitance, heating by means of heating coils or electrical resistance heating, or any other known heating means placed in the heating zone preferably below or between the two surfaces of the rotating conveyor belt. The conveyor belt is preferably perforated or consists of wire, fabric, or the like. When drying with hot air or steam it has been found advantageous when a guide shaft without a filament thread nozzle is used to conduct the hot drying gas through a separate shaft from the filament feed shaft rather than through the filament guide shaft. In such a case the filament guide shaft should have cool gas passing therethrough and may be insulated from the hot gas shaft by means of, for example, an insulating plate. In this connection it may even be advisable to cool the lower part of the filament feed shaft in order to avoid any chimneying effect by the hot drying gases which might disturb the laying of the filament.

The invention will be better understood with reference to several embodiments of apparatus for the effecting thereof as shown in the accompanying drawings. These drawings and the description thereof are given solely for the purpose of illustration and not limitation.

Referring to Fig. 1, a dryer is shown with a filament guide shaft which contains a filament thread nozzle. The filament 2 passes over the guide roll 1 and drops downward through the guide shaft 3 onto the continuously moving conveyor belt 4. The guide shaft 3 is provided with the filament thread nozzle 5 which constricts in a downward direction. A gas inlet 6 is provided in the guide shaft 3 below the top portion of the filament nozzle 5. Gas is blown into this inlet 6 and passes down the guide shaft 3 carrying the filament in its current and positively depositing it on the conveyor belt 4. The conveyor belt 4 is an endless conveyor belt which moves around rollers 8 and 9. Within the space formed by the conveyor belt there are arranged the heating elements 10, 10, etc., which, for example, may be brought into the desired temperature by electric resistance heating. The formation of the loops of the filament on the conveyor belt as it is carried downward thereon by the gas current may be effected by lateral reciprocation of the conveyor belt, or by reciprocation of the feed nozzle or the guide roller 1. The dried filament leaves the dryer through the guide 11 and the moisture laden air is discharged through the discharge opening 7.

' In Fig. 2 an embodiment of the invention is shown in which the drying is effected by the means of hot air. 'An endless conveyor belt 4 rotates around guide rolls 8 and 9 in a closed drying chamber. The conveyor belt 4 may consist of a mesh wire screen, for example. At least one of rollers 8 and 9 is imparted rotary motion in a known manner, preferably by means of a continuously adjustable gearing, so that the velocity of advance of the belt corresponds to the velocity of the drying of the filament on said belt in the chamber. Above the front end of the drying chamber there is arranged the filament feed shaft 3, the lower part of which is cooled, as, for example, by means of cooling coils or the like. The filament 2 passing over the guiding roller 1, through the shaft 3, is passed onto the conveyor belt 4. The filament may be imparted a transverse motion in the manner described in connection with Fig. 1, so that it is positioned in loose loops on the conveyor belt 4 and is withdrawn completely dry at the other end of the chamber through the outlet opening 12 which is kept as small as possible. Alongside the filament feed shaft 3 there is arranged the hot air shaft 13 through which the drying air is blown or sucked into the chamber from above. Between the hot air shaft 13 and the filament guide shaft 3 there is provided an insulating zone 14 which prevents any heating of the filament guide shaft. The hot air is discharged on the lower side of the apparatus through the discharge shaft 15 by means of a suitable suction device. In order to prevent air circulation in the front, cool part of the apparatus, the drying chamber proper is separated from the cooling chamber by a flap valve 16 which can be placed in any desired position in order to regulate the relative amounts of cold and hot air drawn in through shafts 3 and 13.

In Figs. 3 and 3a a bar type draw-off roll is shown, such as is preferably used as feed member 1, in Figs. 1 and 2. In this connection 17 designates the lateral limiting discs with the central axis shaft 18 and the filamentengaging bars 19. Eight bars have been shown in the figure by way of example, but this number may be increased or decreased, depending on the intended use and the size of the draw-01f roll.

Figs. 4a and 4b show the producing of an oscillatory motion in the free falling filament by means of such a draw-off roll, which for the sake of greater clearness is shown in Figs. 4a and 411 provided with only three bars. The horizontally entering filament is conducted over and in contact with the bars 19 and is passed downward through the guide shaft. The position of the downwardly passing filament 2 as shown in Fig. 4a is determined by the position of the bar 19a. As the draw-off roll continues to rotates, the bar 19a rotates toward the left and the position of the downwardly passing filament is continuously, correspondingly moved toward the left until the position as shown in Fig. 4b is reached. Upon reaching this position, the position of the downwardly moving filament is taken over by the bar 19b which moves the filament to the right until the bar 1% will be in the position shown in Fig. 4a for 19a and then lead the filamen again to the left until the position shown in Fig. 4 is reached again with the bar being in the position of the bar 19b and the bar 19b being in the position of 19a. In this manner the filament is reciprocated back and forth and laid in loose loops on the conveyor belt 4.

The draw-off roll has a relatively rapid speed and thus the filament is imparted equal impulses to the left and right which produce a swinging of the freely falling por- Itjioln thereof which forms the loose loops on the conveyor Of course, the use of such a bar type draw-01f roll is not limited to the production of transverse motion, but can also be used advantageously, for the reasons indicated above, in all places where it is desired to draw off or convey in a smooth motion a filament and particularly a moist filament.

We claim:

1. Device for the tension-free drying of fine filaments which comprises means defining a substantially enclosed drying chamber having an endless conveyor belt positioned therein, heating means positioned to heat a filament carried on said belt, means defining a filament feed shaft into said chamber positioned for passing a downwardly moving filament onto said conveyor belt for passage through said chamber, means defining a bar type draw roll positioned above said feed shaft for the passage of filament thereover whereby the filament is imparted a transverse reciprocal motion during its passage down through said feed shaft, and means defining a filament exit from said chamber for passing a filament out of said lchamber after passage therethrough on said conveyor elt.

2. Device according to claim- 1 in which the said heating means are defined by a heating gas inlet position above said conveyor belt, and including insulating means positioned between said feed shaft and said heating gas inlet.

3. Device according to claim 2 including cooling means positioned for cooling gas passing through said feed shaft.

4. Device according to claim 1 including ventilator means positioned for drawing off resulting vapors from said heating chamber and thereby causing a gas current "through said feed shaft.

5. Device according to claim 4 including valve means positioned to prevent air circulation in the front, cool portion of said drying chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,336,019 Kline et a1 Dec. 7, 1943 2,379,824 Mummery July 3, 1945 2,486,903 Wormell Nov. 1, 1949 2,598,000 Knopp et a1. May 27, 1952 

